Mechanically alloyed magnesium-based materials For hydrogen storage

Abstract

Mechanical alloying is very promising technique for fabrication of hydrogen storage materials possessing good hydriding properties. Magnesium and magnesium-based alloys are attractive from hydrogen capacity point of view, but the kinetics of hydridingdehydriding of magnesium are not sufficiently fast even at elevated temperature. Moreover, the theoretical hydrogen capacity is never achieved in practice. In this work, various approaches to improving hydrogen storage properties of magnesium-based materials with the help of mechanical alloying are discussed and some experimental results illustrate the possibility of each approach. It is demonstrated that improving the hydrogen storage properties of known hydrogen absorbing materials is possible by affecting their structure, morphology, surface properties and so on, using mechanical activation and mechanical alloying with various types of additives. It is possible to search for new hydrogen absorbing materials by means of mechanochemical fabrication of metastable composites of components very different in nature including thermodynamically immiscible ones. These composites may possess very interesting hydrogen storage properties and serve as precursors for the synthesis of new phases. Direct synthesis of metastable intermetallic compounds or hydrided phases in the course of mechanical alloying also opens opportunities to obtain materials promising for hydrogen storage.